Kuo believes that Apple will decide between glass, plastic, and ceramic casing for its 2017 iPhone, but that the company will ultimately settle on glass, much like the iPhone 4, "as plastic doesn’t offer thin and light form factor designs, and it would be not easy to precisely control the tolerance of ceramic." Additionally, Kuo reports that Apple’s 2017 iPhone will adopt a curved display with curved glass body. Again building on the iPhone 4 design, the device will feature a glass front and back with metal sides. Kuo also says the phone will feature a "completely new form factor design" with more narrow bezels and a "more comfortable grip."